In recent years, colorization, digitization, and speeding up of printing apparatuses have advanced, and such advanced printing apparatuses on some level have began to prevail. Use applications of such printing apparatuses are not only markets mainly including the office equipment field such as offices and the like but also become diffused to the printing business field that requires advanced bookbinding and the like. For example, a POD market has been examined in recent years. This market is in the following environment. That is, an operator who undertakes a printing request from a customer operates a printing apparatus to generate a print product that the customer wants. Then, the print product of a final product as an article is delivered to the customer, thus getting a reward from the customer (see Japanese Patent Laid-Open No. 2004-310746).
In the above POD market, a case is assumed wherein the customer often requires various kinds of post-processing such as bookbinding, stitching, and the like for printing materials printed by the printing apparatus. In addition, a case is assumed wherein the customer requires not only single-sided printing but also double-sided printing as a printing mode of data to be output.
Therefore, in order to cope with such cases, it is desired to improve functions associated with double-sided printing provided by the printing apparatus not to a level required in the office environment but to a level that can meet the needs required in the POD market. For example, a printing apparatus which comprises a function designed with advanced post-processing required in the POD environment in place of a simple double-sided printing function is to be provided. In other words, it is desirable to provide a printing apparatus which can suppress a double-sided printing result which is useless as an article from being printed out, and can generate a double-sided printing result with high precision. For example, it is desirable to provide an advanced double-sided image alignment function or the like under the condition of post-processing or the like.
Upon delving the above items to be examined, in general, in an office environment, printing materials printed by the printing apparatus are rarely bound up as an article. For example, in the office environment, even if the positions of images printed on the front and back sides of a printing material in the double-sided printing mode are misaligned, that print product is not handled as an article. Hence, the user neither regards nor sees such product as a problem.
On the other hand, in the POD environment, a case is assumed wherein a print product is bound up as a manual, guide book, or the like, and is delivered as an article to the customer. In addition, the print product to be bound up may undergo double-sided printing on the front and back sides of a single printing material in some cases. In such case, if the printing position of an image printed on the front side of the printing material is misaligned from that of an image printed on the back side of the printing material, the print product is unlikely to be adopted as an article. Such print product is more unlikely to be adopted with increasing degree of misalignment (misalignment amount) between the printing positions of images on the front and back sides. In this manner, the position misalignment of the printing result of the images on the front and back sides in double-sided printing, which is not apprehended in the office environment, must be coped with in the POD environment in some cases.
Upon further delving the above examinations, the position misalignment between the images on the front and back sides of a printing material in double-sided printing results from, e.g., the alignment precision of a printing material in the printing apparatus. For example, if the product specification associated with the alignment precision of images on a printing material of the printing apparatus itself is 2 mm, the positions of images on the front and back sides are likely to be misaligned by a maximum of 4 mm. If the printing apparatus outputs such printing result in which the positions of images on the front and back sides are misaligned by 4 mm under such product specification, such position misalignment is on a negligible level in the office environment.
However, a print product which suffers even the position misalignment which is on the negligible level in the office environment is unlikely to be adopted as an article in the POD environment. In this manner, in the POD environment, when the operator detects the position misalignment on such level upon inspecting a print product as an article, it is more likely to be re-printed. Such image position misalignment phenomenon may take place due to, e.g., shrinkage of a printing material (to be also simply referred to as a sheet hereinafter) under the influence of environmental changes of an ambient temperature, humidity, and the like while the printing apparatus conveys the printing material. In this manner, the above phenomenon takes place due to not only internal causes of the printing apparatus itself but also external causes surrounding the printing apparatus.
Under such circumstances, on the actual spot of the POD environment, the operator may be required to have advanced skills and to do many works so as to suppress the above situation upon execution of double-sided image printing for bookbinding. For example, the operator manually performs fine adjustment of image positions of image data input to the printing apparatus based on his or her empirical rules from the beginning while calculating the misalignment amount. Also, the operator aligns images by executing pre-printing or the like.
Upon completion of the alignment work of images on the front and back sides through a variety of operations, the operator finally saves the image data that has undergone the image alignment, and performs actual printing using the saved image data. In some cases, the operator on the spot of the POD environment is required to do such advanced and complicated works.
As described above, the alignment precision of a printing material in the printing apparatus may change due to a plurality of factors such as the environmental conditions, i.e., the ambient temperature, humidity, and the like of the installation location of the printing apparatus, shrinkage of a sheet upon fixing, displacement in a paper convey path, and the like. In other words, the image position misalignment amount may dynamically vary on a dairy basis. Therefore, even if the image data which has undergone image alignment on the front and back sides by the aforementioned method can be saved to be re-usable even after it is printed once, that image data cannot be used intact in the next printing processing. That is, even when identical image data is re-usably held, the operator must consequently redo image alignment every time that data is used. From such viewpoint, a reduction of the work load on the operator upon performing image alignment will be further pressed in the future.